D. R. Cushman and J. W . Schick Mobil Research and Development Corp., Paulsboro, N. J.
Three papers covered differential thermal analysis. Anisimov et al. (1E) used an automatic recording potentiometer, with sand as an inert standard, to provide thermograms which described phase transitions of paraffin waxes, ceresins, microcrystalline waxes, and their mixtures. Craig et ai. (6E) studied paraffin, polyethylene, natural waxes, and mixtures of paraffin with beeswax or carnauba. The data suggested that the waxes interact and do not form true mixtures. Giavarini et al. (8E) reported a new method for determining paraffin in mineral oils by measurement of heats of fusion and crystallization with a differential scanning calorimeter, Chromatography was covered by four papers. Sojak and Bucinska (22E) used gas chromatography to determine n-alkanes in desorbates from the dewaxing of gas oil. Streibl and StrAnskJi ( B E ) reported on the synthesis and gas chromatography of higher cyclohexyl and other paraffins. Correlations were obtained between retention volume and number of C atoms and position of substitution. The technique is intended for application to natural waxes. Dobies (7E) used a thin-layer chromatographic method for determining ultraviolet absorbers in paraffin wax. The UV absorbers, typical of benzophenone type, are first extracted from the wax with alcoholic KOH. Reutner (21E) analyzed several commercial waxes by thin-layer chromatography. Eluents were benzene, benzene and 0.5% acetic acid, benzene and 201, methyl acetate, tetrachloroethylene, and tetrachloroethylene and 0.5% acetic acid. The use of urea adduction procedures was covered by five papers. Brink and Kleynjan (4E) formed adducts homogeneously in n-propanol solution a t 140 "C under pressure for waxes freezing below 65 "C, and in n-propanol-toluene solution a t 140 "C for higher melting waxes. Balitskii (2E) separated paraffin into fractions by formation of complexes with urea, adsorption on molecular sieves or active carbon, and determined the composition of the fractions by chlorination or nitration and by X-ray and I R analysis. Markaryan and Kazakova (16E) reported the composition of several waxes as determined by fractional crystallization, chromatography on SiOz gel, and complexing with urea. Kisielow and Kajdas (15E) purified crude paraffin wax by a combination of extraction with urea and other techniques, including vacuum distillation, fractionation with 170R
less than an equivalent amount of urea, and extractive crystallization with urea. Kajdas (1OE)reported on the composition and properties of the saturated petroleum slack wax fraction after deparaffination with urea. The fraction unreactive toward urea was fractionally distilled. Each fraction was separated on silica gel into aromatic and saturated hydrocarbon components, the latter being further resolved by extractive crystallization from benzene with thiourea. Kajdas and Tuemmler (13E) described an electron-attachment mass spectrographic procedure for analysis of solid saturated hydrocarbons from slack wax. The wax was fractionated by urea adduction, silica gel chromatography, vacuum distillation, and extractive crystallization with urea. The saturated fractions were examined by electron-attachment mass spectrometry. The same authors, in another paper (14E),described a similar study. From the spectra of the samples, the content of paraffin hydrocarbons, monocyclic, dicyclic, and other polycyclic naphthenes was calculated. Mead (18E) reported on field-ionization mass spectrometry of heavy petroleum fractions. Wax fractions in the 300-550 "C boiling range were analyzed. A double-focusing mass spectrometer and razor blade emitter were used. For two ASTM reference waxes, results agreed with tests using conventional mass spectrometers. Kajdas (12E) studied high-boiling hydrocarbons of slack wax by methods involving molecular mass spectrography, IR, UV, and NMR spectrometry, and determination of density, refractive index, viscosity, molecular weight, and melting point. The same author (11E) gave a review of analytical methods and aspects of the composition of solid petroleum hydrocarbons. Mass spectrometry combined with gas chromatography or I R spectrography was found especially useful in research on petroleum waxes. Mikhailov (19E) determined the composition of hard paraffins from highand low-S Russian crudes by modern analytical procedures. A thorough understanding of composition was needed in connection with subsequent oxidation of the waxes to pyoduce fatty acids. Szergenyi (24E) reported the composition of macro- and microcrystalline paraffins from Romaskino petroleum. Paraffins and ceresins were separated into paraffinic, aromatic, and mixed naphthenic and isoparaffinic hydrocarbons by chromatography and adsorption on molecular sieves. Branched chains and cyclic structures were separated from n-paraffins with molecular sieves. Three papers covered infrared spec-
,ANALYTICAL CHEMISTRY, VOL. 43, NO, 5, APRIL 1971
trometric determinations. Berthold (8E) examined 98 hydrocarbons of different types (mol wt 80 to 500). A rectilinear relationship was obtained between the proportion of methyl groups in the molecule and the maximum extinction coefficient. Guseva and Leifman (9E) found IR spectra to reflect phase transitions in hydrocarbon fractions studied. Changes in absorption were associated with the formation of a hexagonal structure on solidification and a rhombic structure by polymorphic transition. Martin and Heaton (IYE) made infrared determinations of stearyl methacrylate-cetyl methacrylate copolymer in paraffin, and developed an IR differential absorption method whereby the copolymer can be determined a t concentrations as low as 0.003% in wax. Costantinides and Schromek (6E) used the electron microscope to study the disturbing action of asphaltenes, resins, and petroleum distillate pour point depressants on the crystallization of a microcrystalline paraffin wax from heptane solution. Rakos (2OE)investigated the artificial aging of paraffin by means of an NMR spectrometer operating a t 100 Mc. In addition to the signal of the CH: and CH2 groups, a new signal, which was not present in the spectrum of the paraffins not subjected to aging, appears after 23 hours aging.
J. A. Wronka Cifies Service Oil Co., Cranbury, N. J.
Fenijn (638') described a penetrometer on which the output of a displacement transducer fed to a recorder was substituted for the indicating dial of a standard penetrometer. An automatic potentiometer controller permitted the choice of any desired load time. Gill (64F) described a cylinder viscometer for the measurement of the viscosity of paving asphalts and viscosity changes of recovered materials after natural aging and weathering in the range of 108-101' poises and Valayer (4OF) miscellaneous pieces of equipment such as a triaxial cell to test stress-strain-time relations, a compacting machine and lathe for sample preparation, etc. Masek ( S 2 F ) characterized fifteen bituminous materials from Czechoslovakian crudes using thermogravimetric analysis in an argon stream by recording the total weight loss on heating from 20" to 1000 "C a t 5 "c/ min. and the partial loss at 25 "c intervals so as to locate the beginning and maximum of weight loss. Dickie et al. (17F) examined two petroleum resins using high-resolution mass spectroscopy as a first attempt to
